The present invention relates to frequency synthesizers, and in particular, to wide bandwidth fast hopping frequency synthesizer circuits and methods.
Many electronic systems require signals at a variety of different frequencies to perform a variety of different functions. In many situations, a system will include some reference frequency (sometimes referred to as the system frequency). An example of such a reference frequency is a system clock. The reference frequency often provides the foundation timing reference for the system. However, many system components and subsystems may require different frequency signals to operate properly. In many cases, subsystem frequencies may vary drastically from the reference, or may have different tolerances or other unique requirements that the reference frequency cannot meet. Thus, frequency generation, which is sometimes referred to as frequency synthesis, is an important consideration in the design and development of electronic systems.
Many communication systems utilize mixers to transmit electromagnetic signals. Mixers inherently have nonlinearities which may generate spurs. High frequency synthesizers may utilize several mixers which may introduce spurs spreading over a wide bandwidth. This especially becomes a problem when bandwidths are restricted by government regulation. For example, Europe and Japan have a restricted bandwidth between 4.8 Ghz and 5 Ghz. Commercial products cannot produce carrier frequencies within this band nor can they produce any significant spur within this band. Therefore spurs can limit government compliance or may limit the usable bandwidth available.
Thus, there is a need for new frequency synthesizers. The present invention solves these and other problems by providing wide bandwidth fast frequency hopping synthesizer circuits and methods where the synthesizer output can hop over a very wide bandwidth with minimal spurious generation. In one embodiment, the frequency hopping time of proposed solution is few nanoseconds